Intestinal Ca2+ absorption revisited: A molecular and clinical approach

Table 1 Effects of pro-oxidant conditions on intestinal Ca²⁺absorption and associated parameters

Pro-oxidant condition	Effects on genes and proteins involved in intestinal Ca2+ absorption	Effect on REDOX state	Effects of antioxidant/ protective molecules	Effects on apoptosis
BSO[147,148]	Inhibition of IAP activity	Decrease in GSH content	GSH administration normalized intestinal Ca2+ absorption	Not evaluated
MEN[149-156]	Decrease in PMCA1b gene-protein expression and activity. Decrease in CB D28k and CLDN 2 gene-protein expression	Depletion of GSH content; Increase in ROS and protein carbonyls; Enhancement in SOD and CAT activity	QT, MEL and GLT administration normalized intestinal Ca2+ absorption and associated parameters	Activation of intrinsic and extrinsic pathways
NaDOC[162,165]	Decrease in PMCA1b mRNA Inhibition of PMCA1b, CBD28k and NCX1 protein expression	Depletion of GSH content; Increase in ROS and activity of SOD, CAT and GPx; Increase in iNOS protein expression and NO• content	QT and UDCA administration avoided the inhibition of intestinal Ca2+ absorption caused by NaDOC	Activation of intrinsic and extrinsic pathway
Diabetes[166]	Enhancement in expression of NCX1, PMCA1b and TRPV6 proteins and CLDN 2 gene expression	Decrease in GSH content; Increase in SOD activity and ROS levels	Insulin treatment restored redox state and intestinal Ca2+ absorption	Not evaluated
Metabolic syndrome[167]	Decrease in TRPV6, PMCA1b, CB D9k, CLDN 2, CLDN 12 and VDR protein expression; Decrease in IAP activity	Enhancement in protein carbonyls, NO• levels and nitrotyrosine content in proteins; Decrease in SOD and CAT activity	Administration of NAR prevented the reduction of intestinal Ca2+ absorption caused by fructose-rich diet	Not evaluated

BSO: DL-buthionine-S, R-sulfoximine; CAT: Catalase; CB D_28k: Calbindin D_28k; CB D_9k: Calbindin D_9k; CLDN 2: Claudin 2; CLDN 12: Claudin 12; GLT: Glutamine; GPX: Glutathione peroxidase; GSH: Glutathione; AP: Alkaline phosphatase; MEL: Melatonin; MEN: Menadione; NaDOC: Sodium deoxycholate; NAR: Naringin; NCX1: Na⁺/Ca²⁺ exchanger; NO^•: Nitric oxide; PMCA_1b: Plasma membrane Ca²⁺ATPase; QT: Quercetin; SOD: Superoxide dismutase; TRPV6: Transient receptor potential vanilloid type 6; UDCA: Ursodeoxycholic acid; VDR: Vitamin D receptor.